First my sense is that part of your concern is related in some way to a bitter divorce and making sure that that ex of yours is punished in addition to any concern for your daughter's welfare.
If the trust was created under his mother's Will, then you, or more wisely, a professional can go to the Surrogate's Court in the county she was a resident and looking at the Will and see the terms of the trust and the stated purpose of the trust (if any).
There may be restrictions in the trust with respect to such things as investing the trust assets, where the assts must be held, etc.
For example, if it says for college only, then anything inconsistent with that should be prohibited. On the other hand if it says for her benefit, then there could be a legitimate question as to whether or not a purchase of a new house as a trust asset, which she would live in, is appropriate, particularly if he is a custodial parent.
The Surrogate's Court could remove a trustee who is abusing the trust, require the abuser to make amends, and would appoint another trustee, typically a local bank or trust company. That would require you to have a lawyer assisting and representing the daughter's interests.